The present invention relates generally to a fuel system for internal combustion engines that enables the invention to utilize alternative fuels; and, more particularly to an improved fuel system for an internal combustion engine and an adapter and spark plug for use in same.
The problems of air pollution caused by automobiles, lawn mowers and other vehicles that have internal combustion engines powered by gasoline is well documented. This problem is particularly described in an article in the San Diego Union Tribune, Wednesday, Sep. 25, 1996 and in Popular Science, August 1996. Indeed, under the Clean Air Act, in the next few years cars that do not run on standard fossil fuels like gasoline will be required in several states. Currently, there are no vehicles available to meet this need.
Thus, it will be appreciated by those skilled in the art that there has been a push to seek other fuels for use in internal combustion engines. These fuels include methane, propane and gasohol.
Hydrogen has also been characterized as a promising fuel source. See Department of Energy publication entitled "Hydrogen Fuel", printed in 1978, U.S. Government Printing Office, U.S. Department of Energy, Office of Public Affairs, Washington, DC 20585. Particularly, the graph presented in FIG. 6, which is copied from this publication, shows the potential for hydrogen in BTUs/Lb. However, the mass energy density for hydrogen is low; and thus, hydrogen needs to be compressed before its energy potential can be realized. Hydrogen is a "dry fuel" that is more difficult to ignite than "wet fuels." It becomes more difficult to ignite when it is cooled. However, cooling is preferred in most systems to avoid premature ignition of the fuel. Other systems deliver the hydrogen under pressure to prevent ignition in the supply line, which is a form of pre-ignition. No prior art fuel system has been able to capture the energy of hydrogen.
Several fuel systems for use with hydrogen have been proposed. Examples are described in U.S. Pat. Nos. 4,167,919; 4,253,428; 4,016,836; 4,178,882; 5,222,993; 5,085,176; and 5,085,176. The problem with these prior art fuel systems is they cannot take advantage of the alternative fuels to generate sufficient power from the fuels to drive an internal combustion engine for use in a lawn mower, automobile or other vehicle. As noted above, this is a particular problem when hydrogen is used as a fuel. Additionally, the prior art systems do not address the problem of back fire, i.e. undesired explosion of the fuel in the cylinder during the exhaust stroke of the internal combustion engine.
Premature ignition or backfire is often a problem with hydrogen fueled systems. U.S. Pat. No. 4,383,198 (Hosking) teaches a fuel injection spark plug with a pre-cooling chamber to avoid premature ignition indentination of a gaseous fuel supplied to the spark plug. U.S. Pat. No. 4,383,198, Hosking, entitled "Fuel Injection Spark Plug", issued May 10, 1983, is hereby incorporated herein by reference. However, cooling hydrogen makes it more difficult to ignite. This is because hydrogen is a dry fuel whereas gas is generally considered a wet fuel. Thus to reduce fuel pollution one prefers to utilize a fuel such as hydrogen and ignite it with a hotter spark.
One patent discussing very high energy (VHE) ignition systems is U.S. Pat. No. 5,207,208 issued to Ward, entitled "Integrated Convertor High Power CD Ignition", issued May 4, 1993. U.S. Pat. No. 5,207,208 is hereby incorporated herein by reference. Pat. '208 teaches very high energy ignition systems, for instance on the order of 36K volts. It teaches voltage doubling utilizing pulsating sparks of peak current on the order of two amps. While 36K volts may at times be adequate, it is preferable to achieve a higher voltage in the ignition chamber when using hydrogen.
It is known in the art to use a direct ignition system, also referred to as a distributorless ignition system, to increase the spark plug voltage. Such direct ignition systems use a "waste spark" method of spark distribution. Each cylinder is paired with its opposing cylinder in the firing order (1-4, 2-3, on a four cylinder, 1-4, 2-5, 3-6 on a V6) so that one cylinder on compression fires simultaneously with its opposing cylinder on exhaust stroke. Since the cylinder on exhaust stroke requires very little of the available voltage to fire its plug, most of the voltage is used to fire the cylinder on the compression stroke.
U.S. Pat. No. 4,462,380 discusses a distributorless ignition system. U.S. Pat. No. 4,462,380 entitled "Enhanced Spark Energy Distributorless Ignition System" issued Jul. 31, 1984 by Asik is hereby incorporated herein by reference. Pat. '380 teaches a distributorless ignition system of an internal combustion engine which has a supplementary spark energy module to increase spark energy. Each high voltage terminal is connected to a single spark plug and each ignition coil primary is alternately energized and quickly de-energized, producing opposite polarity ignition voltages at each coil terminal. As a result, pairs of spark plugs are alternately fired, with each firing pair occurring in a compression or exhaust stroke and thereby providing the proper ignition to the engine. Asik asserts that firing a spark plug does not affect engine performance or emissions. As taught by the instant invention this is incorrect for hydrogen fuels when the exhaust is sparked at a sufficient voltage.
U.S. Pat. No. 5,146,882 (Brinkman) teaches use of specific wet fuel mixtures in conjunction with direct ignition systems (D.I.S.). It teaches that technical breakdown voltages for typical spark plugs are on the order of 15-20 kV and DIS typically yield between 30 kV-40 kV. U.S. Pat. No. 5,146,882, entitled "Method And Apparatus For Cold Starting A Spark Ignited Internal Combustion Engine Fueled With An Alcohol-Based Fuel Mixture", by Brinkman, et al., issued Sep. 15, 1992, is hereby incorporated herein by reference. The previously referenced prior art discusses alternate fuels and fuel systems but does not teach a method of achieving a sufficient voltage with a hydrogen system.
What is needed, then, is a fuel system for an internal combustion engine that provides a way to generate sufficient power from the alternative fuels and that reduces backfire problems. Such a system is lacking in the prior art. Also lacking in prior art is a system utilizing alternate fuels with reduced pollution capabilities. Also lacking is a way of generating sufficient voltage spark to ignite the alternate fuel.
The following U.S. Patents discuss spark plugs designed for gas internal combustion engines to reduce radio frequency noise and interference. U.S. Pat. No. 4,224,554, entitled "Spark Plug Having A Low Noise Lever" issued to Nishio et al., Sep. 23, 1980 is hereby incorporated herein by reference. U.S. Pat. No. 4,029,990 entitled "Spark Plug Construction" issued to Nagy et al., Jun. 14, 1977 is hereby incorporated herein by reference.